This proposal aims at elucidating the mechanisms of hemoproteins and enzyme action using magnetic resonance spectral techniques. With human hemoglobins, the mode of oxygen binding, the interaction with organic phosphates, the relationship between the protein conformation and the heme-spin state, and the mechanism of cooperative oxygenation will be studied by EPR, observing the 17O superhyperfine interaction in Co2 ion-hemoglobins, and by the proton and phosphorus NMR and nuclear relaxation techniques. A comparative study of human normal and sickle hemoglobins is being carried out using nuclear relaxation and gelation techniques and has resulted in the discovery of gelation of sickle oxyhemoglobin in the presence of inositol hexaphosphate. The latter observation may provide the basis for a simpler clinical test for screening of patients for hemoglobin S. The arrangement and conformation of enzyme bound substrates of several kinases and a synthetase reaction will be determined by nuclear relaxation techniques using Cr3 ion-nucleotide complexes as substitution inert, paramagnetic analogs of Mg2 ion-nucleotides. The role of metal ions in the catalytic mechanism of phosphoryl-transfer enzymes will thereby be clarified. The nature of the titratable group controlling the catalytic function of carbonic anhydrase will be investigated by NMR and visible absorption studies on Co3 ion-carbonic anhydrase. Comparative nuclear relaxation studies of the conformation of enzyme bound organic substrates to Mn2 ion and Co2 ion-carbonic anhydrases will be carried out to determine the detailed modes of substrate binding and to determine why the Mn2 ion-enzyme is less active. A detailed understanding of the structure and mechanism of proteins which is the ultimate aim of the proposed research is fundamental to a knowledge of biochemical pathways of life at the molecular level and may provide new insights for the treatment of diseases arising from molecular abnormalities.